A transportation network is any navigable system of roads, pedestrian walkways, paths, rivers, shipping lanes or other network that is utilized to transport humans or vehicles. A transportation network can also include combinations of routes for the above modes of transportation. These combinations of routes are referred to as multimodal transportation networks. A segment of a transportation network (referred to as a transportation network segment) is a portion of the transportation network that represents a path of travel for a vehicle or pedestrian without a method of entry or exit other than at its end points.
One method of creating or updating a digital transportation network is by traversing paths/elements of the transportation network with highly specialized location measuring and recording systems designed for this purpose. In alternative methods, transportation network information is gleaned from aerial images or compiled from existing localized digital transportation networks. In addition, combinations of the above methods can be utilized.
More recently, probe traces acquired from location sensors carried in a series of uncoordinated vehicles or by numerous pedestrians has been used for creating/updating and/or refining a transportation network. Probe traces are a plurality of sequential location measurements from location sensors. Location sensors are usually part of a navigation system or housed in a multi-purpose device such as a smartphone.
Utilization of uncoordinated probe traces has generally been limited to updating an existing transportation network because the approximate location of transportation segments must be known in order to determine if a given probe trace traverses a particular segment. Thus, probe traces are typically used only to refine and improve accuracy. Conventionally, digital transportation networks are not generated or built (e.g., created from scratch) based on uncoordinated probe traces. In addition, the conventional art does not address the junction of transportation network segments in an automated fashion.
Moreover, location measurements from a single location sensor are typically not sufficiently accurate to generate a digital transportation network for certain applications such as an Advance Driver Assistance System (ADAS). For example, positional accuracy for a road network in an ADAS should be less than about 5 meters. But, typical location measurements from conventional location sensors are on the order of about +/−10 to 15 meters.